Sprinkle a couple of pinches of salt over both sides of the fish. Let sit for 15 minutes. Then pat dry with paper towels.

Heat oil in a frying pan at medium heat, and cook fish 2 minutes or so on each side until nicely browned. Remove fish from the pan. Clean the pan with a paper towel, and cook sugar, Soy Sauce, Sake and Mirin in the same pan. Reduce for a couple of minutes and add fish back. When the sauce has slightly thickened, remove from heat.